It's Christmas and Blair and Serena are best friends again and up to their old tricks - partying hard and breaking hearts from Park Avenue to the Caribbean.

Blair's mother and Cyrus are having their honeymoon in Salt Key. And when school finishes, Blair, Serena, Aaron and company head down to blow off steam after their exams, and in between Pina Coladas, Blair and Serena plot revenge on super-jerk Chuck Bass.Then it is back to NYC for Serena's New Year's Eve party, during which Nate and Blair need to sort out their relationship, and Serena may or not be revealed to be the secret fling of Hollywood's hottest young leading man . . .